NEW BIOLOGIC FORMS OF PUCCINIA GRAMINIS* 



[PRELIMINARY PAPER] 



By E. C. Stakman, Head of Section of Plant Pathology, Department of Plant Pa- 

 thology, Botany, and Department of Agriculture, University of Minnesota; M. N. 

 LEVINE, Field Assistant, Bureau of Plant Industry, United States Department of 

 Agriculture; and J. G. LEAch, Shevlin Fellow, University of Minnesota 



COOPERATIVE INVESTIGATIONS BETWEEN THE AGRICULTURAL EXPERIMENT 

 STATION OF THE UNIVERSITY OF MINNESOTA AND THE BUREAU OF PLANT 

 INDUSTRY OF THE UNITED STATES DEPARTMENT OF AGRICULTURE 



Several biologic forms of Puccinia graminis on wheat (Triticum spp.) 

 have been described. Originally P. graminis tritici was supposed to be 

 the only form capable of attacking wheat varieties. None of the com- 

 mon wheats (T. aestivum) was resistant to this form, although several 

 varieties of durum (T, durum), emmer {T. dicoccum), and einkorn 

 (T. monococcum) were either resistant or almost immune. 



The first demonstration that there was more than one form of stemrust 

 on wheat was made in 191 6 when P. graminis tritici-compacti was de- 

 scribed.^ This form proved to be especially interesting and significant 

 because it could not infect the hard spring wheats normally, but developed 

 well on soft wheats. It was also found that many of the hard winter 

 wheats were resistant to the new form. The range of parasitism of 

 the second form was therefore narrower than that of the ordinary 

 P. graminis tritici. But in 191 8 Melchers and Parker^ found that 

 Kanred, Kansas P. 762 (CI 5146),^ Kansas P. 1066 (CI 2879), and 

 Kansas P. 1068 (CI 5880), three selections from the Crimean group 

 made at the Kansas Experiment Station, were almost immune to 

 P. graminis tritici. These selections were also found to be moderately 

 resistant to P. graminis tritici-compacti, and they therefore seemed to 

 be resistant to the stemrust of wheat. Later Melchers and Parker ^ 

 found a form which infected Kanred and the two other selections nor- 

 mally. Levine and Stakman ^ and Leach ^ had begun an intensive 

 study of the parasitic capabilities of forms of P. graminis on varieties 



' Published, with the approval of the Director, as Paper 144 of the Journal Series of the Minnesota 

 Agricultural Experiment Station. 



'Stakman, E. C, and Piemeisbl. F. J. a new strain op puccinia graminis. (Abstract.) In 

 Phytopathology, v. 7, no. i, p. 73. 191 7. 



• Melchers, Leo E., and Parker, John H. three varieties of hard red winter wheat resist- 

 ant TO STEM RUST. In Phytopathology, v. 8, no. 2, p. 79. 1918. 



• CI = Cereal Investigations. 



' Melchers, Leo E., and Parker, John H. Another strain op puccinia graminis. Kans. Agr. 

 Exp. Sta. Circ. 68, 4 p. 1918. 



• Lbvinb, M. N., and Stakman, E. C. a third biologic porm op puccinia graminis on wheat. 

 In Jour. Agr. Research, v. 13, no. 12, p. 651-654. 1918. 



' Leach, J. G. a comparathtb stttdy op the parasitism op puccinia graminis tritici and puccinia 

 graminis tritici-compacti. To be published as master's thesis. University of Minnesota. 



Journal of Agricultural Research, Vol. XVI, No. 3 



Washington, D. C. Jan. »o, 1919 



ra (103) Key No. Minn. 36 



